Electrical control system for liquid fuel burners



Dec. 15, 1953 F. B. AUBERT 2,662,589

ELECTRICAL CONTROL SYSTEM FOR LIQUID FUEL BURNERS Filed Sept. 18, 1947 2Sheets-Sheet l 28 ooocoooc finausea-- Ila INVENTOR.

A in) ATTORNEY Dec. 15, 1953 F U E 2,662,589

ELECTRICAL CONTROL SYSTEM FOR LIQUID FUEL BURNERS Filed Sept. 18, 194728 OOOOOOOO- 2 Sheets-Sheet 2 FIG.2

INVENTOR. 4 6

Patented Dec. 15, 1953 UNITED STATES PAT ELECTRICAL CONTROL SYSTEMFORLIQUID FUEL BURNERS 9-Claims. 1

This invention relates to new and useful improvements in control systemsfor liquid fuel burners.

One of the objects of this invention is to provide an improved controlsystem for liquid fuel burners.

Another object of this invention is to provide a control system for aliqui fuel burner having controllable fuel vaporization means.

Another object of this invention is to provide a control system forliquid fuel burners which is easily constructed. and assembled andinexpensive to manufacture.

Other objects of this invention will become apparent from time to timethrough the specification and claims as hereinafter recited.

In the accompanying drawings to be taken as a part of thisspecification, there are clearly and fully illustrated two preferredembodiments of this invention, in which drawings- Figure 1 is view invertical cross-section of a pot type liquid fuel burner having a fuelvaporization'member and diagrammatically showing a control systemtherefore, and

Fig. 2 is a view of a burner and fuel vaporization member similar tothat in Fig. 1 but having a different control system therefor.

Referring to the drawing by characters of'reference, in Fig. 1 there isshown a liquid fuel burner I having a pot 2 and arecessed fuel wellportion 3. The pot 2 has a plurality of air supply holes 4 therein andis surrounded by an air supply jacket E having a cover member 6 andbeing supplied with air by a blower l. The

fuel well portion 3 opens upward. into the pot 2 through an aperture 3in the lower wall 9.

There is a fuel vaporization member lil-positioned in the fuel wellportion 3 and extending upwardly into the pot 2. The member It has anenlarged hollow end portion H and a smaller solid rod portion l2. Incommercial construction the fuel well portion 3 and fuel vaporizationmember in would be cylindrical in shape although the burner wouldfunction with these members constructed in other shapes. A fuel supplyconduit I3 opens into the lower side wall of the fuel well portion 3through an aperture 14 for supplying fuel for combustion in the burner.The member H3 is operable upon heating to vaporize liquid fuel comingthereagainst for combustion and is of such a size relative to the fuelwell portion 3 that a very small annular space is enclosed between themember It and fuel W811. portion 3 so thata large area of heatingsurface of the member 'Ifl'is provided for a small amount of fuelthereby increasing the efficiency of the transfer of heat for vaporizingfuel. Positioned inside the hollow end portion of the fuel vaporizingmember if: for heating the fuel supplied to the fuel well portion 3prior to combustion is an electrical resistance heater coil I-carried inan insulating member It. The rod portion [2 of the fuel vaporizingmember I0. extendsupward through the pot 2 into the zone of combustionand is operable during combustion to conduct heat to the hollow endportion l I for the vaporization of fuel. The supply of fuel through theconduit E3 to the fuel well portion 3 is controlled by an electricallycontrollable valve ll such as a solenoid valve or a valve operated by.an electrically energizable heat motor. The ignition of fuel in theburner not 2 is accomplished by an electric spark ignition ifl such as aspark plug.

The-control system for the burner l is supplied with power from a'mainpower source I9 to the primary of a transformer 2!. From the secondary22 of the transformer 2| a conductor 23 leads to the fixed contact 2d ofa room thermostat 2-5. The thermostat 25 is of a conventional typehaving a fixed contact 24 and a movable contact 26 carried by abimetallic blade 21. The room thermostat has an electric heater coil 28which functions as a compensator for fluctuations in temperature towhich the thermostat responds. The heater coil 28 is connected by aconductor-29 to a resistor 30 which is in turn connected to thetransformer secondary 20 as at 31. From the bimetal blade 27 of thethermostat 25 a conductor 32 runs to the coil 33 of the relay switch 34.The relay switch as is a bi-pole switch having two fixed contacts 35 and36 and two-movable contacts at and 38 carried by contact arms 39 andrespectively, contact arms 39 and ii] beingconnected to each other forjoint movement by a connecting member at of an electric insulatingmaterial. From the relay coil 33 a conductor fizruns to a connectionpoint 43 on a conductor 44 which interconnects the fixed contact 35 andthe fixed contact d5 of a thermostatic switch 4E. The thermostaticswitch 45 has three fixed contacts '45. ll and 38 and three movablecontacts 49, 59 and 5!. The movable contact 69 is carried by a contactarm 52 and the movable contacts so and El are carried by a contact arm53. The contacts 45 and 49, 418 and Si are initially closed and thecontacts 47 and 50 are initially open so that movement of thethermostatic switch 46 will open the closed contacts and close the opencontacts. The contact arms 52 and 53 are connected each to each by anactuating member 54 of an insulating material which is in turn connectedto and actuated by a bimetallic blade 55. From the contact arm 52 of theswitch 46 the conductor 56 connects with a conductor 51 which runs fromthe relay switch contact arm 39 to the connection point 3| on thetransformer secondary 22. From the main power source l9 and connected inparallel with the transformer primary 29 a circuit runs by conductors 58and 59 to the electric motor 69 which drives the blower the circuitbeing completed by conductors GI and 62 back to the main power sourcel9. This last-mentioned circuit through the blower motor 69 is such thatthe blower I will be operating at all times that the system isenergized. From a connection point 63 at the junction of conductors 58and 59 in the blower motor circuit, a conductor 64 runs to the fixedcontact 36 of the relay switch 34. From the contact arm 49 of the relayswitch 34 conductors 65 and 66 run to the movable contact arm 53 of thethermostatic switch 46. From the fixed contact 48 of the thermostaticswitch 46 a conductor 6'! runs to a conductor 66 which is in turnconnected to an electrical resistance heater l5, the circuit beingcompleted by a conductor 69 which joins the conductor 62 at a connectionpoint 10 thus completing the circuit back to the main power source IS. Aconductor l! runs from a connection point 12 at the juncture ofconductors 6'1 and 68 to the primary 13 of an ignition transformer 14.The circuit through the ignition transformer 14 is completed back to themain power source H! by conductors i5 and 19 which connect with theconductor 69 at a connection point 17. The conductor 15 leads to thefixed contact 16 of a thermostatic switch 19, the contacts of the switch19 being open so that the circuit through the ignition transformer '14is broken. The thermostatic switch 19 has a fixed contact 18 and amovable contact 39 which is carried by a contact arm ill from which runsthe conductor 16. The switch 19 is actuated by a bimetallic blade 82having an actuating member 83 of an insulating material connected to thecontact arm 8| for movement thereof. From the fixed contact 41 of thethermostatic switch 46 a conductor 84 runs to the electricallycontrollable valve H which is connected by a conductor to a connectionpoint 86 on the conductor 16, the circuit being completed by conductorsI6, 69, and 62 back to the main power source. There is a conductor 86which runs from a connection point 81 at the junction of conductors 65and 66 to a terminal point 88 which is connected to the movable contactarm 89 of a gas tube warp switch 90. The gas tube war switch 99 is ofthe conventional type having a fixed contact 9| and a movable contact 92which is carried by a contact arm 89 of a bimetallic thermostaticmaterial and having an ionizing member 93 which functions to heat thegas within the tube to cause the contact arm 89 to warp closing thecontacts 9| and 92. The fixed contact 9| of the gas tube warp switch 99is connected by the conductor 94 to a connection point 95 on theconductor 84 at the valve ll. The ignition transformer secondary 96 isconnected by a conductor 91 to the spark electrode 98 of the sparkignition in the pot 2. The ignition transformer secondary 96 is alsoconnected to a pair of inductive coils 99 and I00 which are grounded asat NH. The coil I00 is connected by the capacitor I92 to a connectionpoint |03 on the conductor 91 leading to the ignition electrode 98.

A. The coil 99 is connected to the ionizing electrode 93 in the gas tubewarp switch and is operable to actuate the same.

In operation this form of the invention functions as follows:

When current is supplied to the system as from the main power source |9the transformer 2| is energized for operation and the blower motor 60 isenergized by the circuit through the conductors 58, 59, 6| and 62. Atthis point in the operation the blower is turned on and is supplying airto the space enclosed by the jacket 5 and the burner pot 2 to supportcombustion in the burner. When the room thermostat 25 closes calling forheat, a circuit is completed from the transformer secondary 22 byconductor 23, the closed contacts 24 and 26 of the thermostat 25, andthe conductor 32 to the relay coil 33. The circuit through the relaycoil 33 is completed for initial operation through the conductors 42 and44, the closed contacts 45 and 49 of the thermostatic switch 45 and theconductors 56 and 51 leading back to the transformer secondary 22. Whenthe relay coil 33 is thus energized the movable contacts 31 and 38 closeagainst the fixed contacts 35 and 36 respectively. When contacts 35 and31 of the relay switch 34 are closed a holding circuit for the relaycoil 33 is established through the closed contacts 35 and 31 and theconductor 57 leading back to the transformer secondary 22. When therelay contacts 36 and 38 are closed a circuit is completed by conductors58 and 34, the closed contacts 36 and 38, the conductors 65 and 66, theclosed contacts 43 and 5| of the thermostatic switch 46, and theconductors 6'! and 68 through the electrical resistance heater |5 in thehollow end portion of the fuel vaporization member II], the circuitbeing completed back to the main power source by conductors 69 and 62.It is thus seen that when the room thermostat 25 closes calling for heatand energizing the relay switch 34 a circuit is completed through theelectrical resistance heater I5 for heating the fuel vaporization memberHe.

The thermostatic switch 19 is positioned adjacent the fuel well portion3 and is responsive to the temperature of the hollow end portion H ofthe fuel vaporization member H; which is heated by the electricalresistance heater i5. When the temperature of the fuel vaporizationmember ID and end portion reaches a predetermined level, such as thatrequired for vaporization of fuel for initial operation, the bimetalblade 82 will move the contact 89 of the thermostatic switch 19 intoengagement with the fixed contact 18. The closing of the contacts and E8of the thermostatic switch 19 completes a branch circuit from theconnection point E2 of the resistance heater circuit by way of conductorH to the ignition transformer primary 13 which is connected by conductor15, the closed. contacts 8|] and I8, and the conductor 76 to theconnection point 11 on the conductor 69 leading back to the main powersource. Upon energization of the ignition transformer T4, the sparkignition I8 in the burner pot 2 will begin to function and is operableto ignite fuel vapors with which it comes in contact. Simultaneouslywith the occurrence of sparks in the burner pot 2 the inductive coils 99and IE0 will operate through the ionizing electrode 93 to heat the gastube warp switch 90 thereby to close the contacts 9| and 92. When thecontacts 9| and 92 of the gas tube warp switch 99 are closed a branchcircuit is established through the fuel control valve H by way ofconductors 65' and 86 leading from the relay switch 3'4 to the gas tubewarp switch 90 and conductor 94 leading from the warp switch 9D to thevalve I7; the circuit from the valve II being completed by conductors85, 15, 69 and 62 back to the main power source. At this point in theoperation of the system the electric heater I5 is energized for thevaporization of fuel, the ignition I8 is energized and the fuel controlvalve if is opened to permit the supply of fuel to the fuel well portion3. When the fuel supplied to the fuel well portion 3 comes in contactwith the fuel vaporization member I!) at its end portion II the fuel isvaporized and these vapors rise into the burner pot 2 to be ignited bythe ignition I8. After ignition of the fuel and the occurrence'ofcontinued combustion in the burner pot 2 the rod portion I2 of the fuelvaporization member It! is heated to a temperature considerably abovethat at the hollow end portion I I and heat therefrom is conducted downthe member It to the hollow end portion II thereby raising thetemperature of that portion above that maintained by the resistanceheater I5. switch I is positioned adjacent the fuel well portion 3 andis responsive to the higher temperature of the hollow end portion H ofthe fuel vaporization member I8 when heated by the occurrence ofcombustion in the burner pot 2. When the hollow end portion I I of thefuel vaporization member I!) reaches a sufficient predeterminedtemperature above that required for response by the switch E9, thethermostatic switch 46 will move opening the closed contacts 58 and 45,4B and 5! and closing the open contacts ll and 5B. When the contacts 49and d5 of the thermostatic switch 46 are op'enedthe circuit for initialenergization of the relay coil 33 is broken but the coil 33 continues tobe energized'by the aforementioned holding circuit. When the closedcontacts 48 and 5I- are opened the circuit through the resistance heaterI5 and the ignition transformer M is broken thus de-energizing theresistance heateri5 and ignition I8 permitting the warp switch contacts9| and 9 2 to open. The opening of the gas tube warp switch contacts 9!and 92 breaks the circuit through the fuel control valve H but theclosing of the contacts d-I and 58 of thethermostatic switchtiesta'blishes a second circuit therethrough. With theclosing of thecontacts 4'! and 50 a new circuit is established for energization of thefuel control valve I by way of conductor 84 leading from the fixedcontact '41 of the thermostatic switch 56 to the control valve I1 whichcircuit is completed as before, the new fuel valve control circuitmerely bypassing the warp switch 90.

In summation, it is seen that when the thermostat closes calling forheat the relay switch l'i l is energized thus establishing a circuitthrough the resistance heater I5 to heat the fuel vaporization memberII) for vaporization of fuel in the fuel well portion 3. Upon attainmentof a predetermined temperature by the end portion II of the fuelvaporization member It, the thermostatic switch I9 closes completing thecircuit through the ignition transformer It at which time'sparks occurin the burner and. the ionizing electrode 93 is energized andthe warpswitch 96 is thus causedto close thereby'establishinga circuit. throughthe fuel supply control valve. H to permit the flow of fuel to thefuelwell portion .3. When fuel flows into the fuel well portion 13 andis vaporized by contact with the vaporization member I19, the'fuelvaporsrise into the humor The thermostatic pot 2 where they are mixedwith air supplied-by the blower I and ignited by the ignition I 8. Uponthe occurrence of combustion in the burner pot 2 the rod portion I2 isheated by the flames in the burner pot and this heat is conducted to thehollow end portion II causing the temperature of the same to rise abovethat produced by the electrical resistance heater I5. Upon attainment ofa second and higher predetermined temperature by the hollow endportionII of the fuelvapor-ization member Ii] the thermostatic switch 45 isactuated causing the circuit to be broken through the resistance heaterI 5 and ignition transformer I l and establishing a new circuit forenergization of the fuel supply control valve I'I. At this point in theoperation the heat for the fuel vaporization member If] is supplied bycombustion in the burner pot 2 and the resistance heater I5 no longerbeing needed is de-energized. Correspondingly, the ignition i8 isde-energized. When the temperature of the space being heatedrisessufficiently to satisfy the thermostat 25, the same will open thusde-energizing the relay switch 34 and breaking the circuit to the fuelsupply control valve I'I shutting off the supply of fuel and permittingthe system to return to its original initial condition upon cooling ofthe fuel vapor-ization member II! and the thermostatic switches 4'6 and79. Upon a subsequent calling for heat by the thermostat 25 the systemwill again function as heretofore described.

In the form of the invention shown in Fig. 2 the burner and fuelvaporization member and any of the parts of the control system thereforwhich are of similar construction to that shown in the form of theinvention previously described and all parts common to both forms of theinvention will bear common reference characters.

There is a burner I having a pot 2 Witha fuel well portion 3 openinginto the lower wall 9 thereof. The pot 2 has a plurality of holesAtheroin for the supply of combustion air and is surrounded by an airjacket 5 having a cover member 6. The air jacket 5 in thisform of theinvention is of slightly different construction from that shown in theprevious form in that the jacketed air space also encloses the lowerwall 9 of the burner pot '2 and there are a plurality of air supplyholes 5* in the lower wall 9 for the supply of combustion airunderneath. As in the previous form of the invention there is a blower lfor supplying combustion air to the jacketed space enclosed by thejacket 5 and burner pot 21 There is a fuel vaporization member It havingan enlarged hollow end portion II and a smaller solid rod portion I2 forvaporization of fuel supplied to the fuel well portion 3. There is afuel supply conduit it which supplies fuel to the fuel well portion 3through aperture It in the lower outside wall portion thereof. The fuelvaporization member it has an electrical re:- sistance heater I5 carriedby a cylindrical insulating member It which is positioned inside. thehollow-end portion II thereof. The supply of fuel to the fuel wellportion .3 is controlled by an electrically controllable valve I1 andthe ignition of fuel in the burner pot 2 is accomplished by electricalspark ignition 38. There is an annular collar member IE4 which fits overthe rod portion I2 of the fuel vaporization member Iii and restricts theflow of fuel vapor into the burner pot 2 by providing a very narrowannular space for the discharge of fuel vapors for ignition from thefuel well portion 3. The collar member Iii-i also functions to heat fuelvapors coming into the burner pot 2 to cause additional vaporization ofany liquid particles entrained with the fuel vapors entering the pot.Electric current for the energization of the control system for thisform of the invention is supplied from a main power source I9 to theprimary 20 of a transformer 2I. From the secondary 22 of the transformer2! a conductor 23 runs to the fixed contact 24 of a room thermostat 25.The room thermostat 25 is of conventional construction having a fixedcontact 24 and a movable contact 25 carried by a thermostatic bimetalblade 21. There is a compensating heater coil 28 for the thermostat 25which is connected to the blade 2? and is in turn connected by aconductor 23 and resistor 39 to a connection point 3I on the transformersecondary 22. From the bimetal blade 2! of the thermostat 25 a conductor32 runs to the coil 33 of a relay switch 3 The relay switch 34 has twopairs of fixed contacts 35 and 35 and two pairs of movable contacts 3'!and 38. The movable contacts 3! and 38 are carried by contact arms 39and 49 respectively which are connected each to each by an insulatingmember M for joint movement thereof. The relay coil 33 is connected by aconductor 42 to a con nection point 43 on a conductor M which runs fromthe fixed relay contact 35 to a connection point I65 on a conductor Intleading to a movable contact arm I01 of a thermostatic switch I08. Thethermostatic switch I50 is carried by a bracket member I99 which ismounted on the lower wall III) of the air jacket 5 The air jacket 5 hasan aperture HI for the insertion of the helical bimetal actuating memberI52 of the thermostatic switch I08 into the jacketed air spacesurrounding the burner pot 2. The thermostatic switch I98 has twocontact arms H3 and I! which are fixed to and actuated by a rod memberII4 which is in turn operated by the helical bimetal element II2. In thethermostatic switch I58 there are three fixed contacts i iii) and Illand three movable contacts H8, H9 and I20. The contacts H8 and H5, H9and IIS are initially closed and the contacts Ill and I20 initially openso that movement of the thermostatic switch Iil8 will cause the twopairs of closed contacts to open and the one pair of open contacts toclose. From the fixed contact IIS of the switch I08 a conductor 56 runsto the connection point on a conductor 57 which interconnects the relayswitch arm 39 and the connection point 3| on the transformer secondary22. From the main power source I9 and connected in parallel circuit withthe transformer primary 2B is a conductor I2I which runs to the fixed.contact 35 of the relay switch 34. The relay switch arm 40 is connectedby conductor I22 to the movable contact Ili! of the thermostatic switchI08 and a conductor I23 connects the fixed contact H of the thermostaticswitch its to the connection point i2 i to which is connected theelectrical resistance heater I5 which is in turn connected back to themain power source by a conductor I25. From the connection point I24 inthe resistance heater a conductor i2 5 runs to the primary '!3 of anignition transformer i l. The ignition transformer primary i3 isconnected by a conductor I27 to one of the fixed contacts I28 of athermostatic switch :29. The thermostatic switch I has two fixedcontacts I28 and I and two movable contacts |3I and I32, the movablecontacts being carried. by contact arm I33. The thermostatic switch I29is actuated by a bimetallic blade I34 which operates through theinsulating member I35 to move the contact arm I33. From the fixedcontact I30 of the thermostatic switch I29 a conductor I36 runs to themotor 56 of the blower 1 which is connected to the main power source bya conductor I31. The contact arm I33 of the thermostatic switch I29 isconnected to the main power source by a con ductor I38. On the conductor23 from the transformer secondary 22 there is a connection point I39from which runs a conductor I40 to the electrically controllable fuelvalve I1. The fuel valve I1 is connected at a connection point I4I to aconductor I42 which leads to the fixed contact II! of the thermostaticswitch I08. From the connection point MI at the fuel valve I! there is aconductor I43 which leads to the fixed contact SI of a gas tube warpswitch 90. The gas tube warp switch has a bimetal blade member 89 onwhich is carried a movable contact 92 which cooperates with the fixedcontact GI. The warp switch 98 has an ionizing electrode t3 which isconnected to an induction coil 99. The bimetal contact arm 89 of thewarp switch 99 is connected through its supporting member to theconductor I44 which leads to the connection point I05 where it joins theconductor I08 leading to the contact arm I0! of the thermostatic switchI08. The ignition transformer secondary S6 is connected at one end by aconductor 9'! to an ignition electrode 98. From the other end of theignition transformer secondary 96 is connected a pair of induction coils99 and I00 which are grounded as at IOI. The induction coil I00 isconnected by a capacitance I02 to a connection point I83 on theconductor 91 leading to the ignition electrode 98.

In operation this form of the invention functions as follows:

When current is supplied from the main power source I9 the transformer2| is energized for the control of the system. When the room thermostat25 closes the circuit is completed from the transformer secondary 22through the conductor 23, the closed thermostat contacts 24 and 26, andthe conductor 32 to the relay coil 33. This circuit through the relaycoil 33 is completed by conductors 42, 44, and I06, the closed contactsH6 and H9 of the thermostatic switch I08, and the conductors 56 and 51back to the connection point 3! on the transformer secondary 22. Thecircuit through relay coil 33 will cause the relay switch 34 to close.Upon closing 01' the relay contacts 35 and 31 a holding circuit for therelay coil 33 is established through the closed contacts 35 and 31 andthe conductor 51 to the transformer secondary 22 which is independent ofthe circuit through the contacts of the thermostatic switch I08. Whenthe relay contacts 36 and 38 are closed a circuit is com-- pleted fromthe main power source through the conductor I2I, the closed relaycontacts 36 and 38, the conductor I22, the closed thermostatic switchcontacts H5 and H8, and the conductor I275 to the electrical resistanceheater I5 which is connected back to the main power source by theconductor I25. It is thus seen that when the room thermostat 25 closescalling for heat the relay switch 34 is energized and closed and aholding circuit is established therefor. With the closing of the relayswitch 34 the circuit is established from the main power source throughthe thermostatic switch I08 for the energization of the electricalresistance heater I5 which begins to heat the hollow end portion II ofthe fuel vaporization member I0. The thermostatic 9 switch I29 ispositioned adjacent the fuel well portion 3 and is responsive to thetemperature of the hollow end portion II of the fuel vaporization memberI0. When the hollow end portion II of the member I reaches sufficienttemperature the thermostatic switch I29 will move closing the contactsI28 and I31, I30 and I32 respectively thus establishing a circuit fromthe connection point I24 of the electric heater circuit by way of theconductor I26 to the ignition primary I3 and thence by conductor I 21,the closed contacts I28 and I 3|, and conductor I38 leading back to themain power source I9. A circuit is also completed from the main powersource I9 by conductor I3I to the blower motor 60 which is connected byconductor I38, the closed contacts I30 and I32, and conductor I 38 Thusit is seen that when the electrical resistance heater I5 has heated themember ill to a sufiicient temperature to close the thermostatic switchI29 circuits are established energizing the ignition transformer I4 andthe blower motor 60 in preparation for the supplying of fuel to theburner. As Was described in the previous form of the invention when theignition transformer I4 is energized and sparks occur in the sparkignition I8 the gas tube warp switch 90 is activated causing thecontacts 9| and 92 to close. With the closing of the contacts 91 and 92of the gas tube warp switch 90 a circuit is completed from thetransformer secondary 22 by way of conductors 23 and I49 to the fuelvalve I"! which isin turn connected by conductor I43 to "the fixedcontact 9| of the warp switch 90.

From the warp switch 90 the circuit is completed back to the transformersecondary 22 by conductors I44 and I06, the closed contacts H6 and H9 ofthe thermostatic switch we and conductors 55 and 51. At this point inthe operation the "electrical resistance heater I5 has heated the fuelvaporization member I0 to a sufficient temperature to vaporize fuelcoming in contact therewith, the spark ignition I8 is functioningcausing the occurrence of sparks in the burner pot 2 and the activationof the warp switch 90 has caused the circuit to the fuel valve I! to becompleted to open the same for the supply of fuel to the fuel wellportion 3. When the fuel entering the fuel well portion 3 comes incontact with the vaporization member I0 it is vaporized and rises upwardto the burner pot '2 where it mixes with the air supplied from theblower I and is ignited by the spark ignition I8. After ignition of thefuel vapors in the burner pot 2 the temperature of theair at thejacketed air space around the burner pot will rise above a predeterminedvalue at which time the bimetal element II2 will cause the thermostaticswitch I08 to move. Upon movement of the contact arms of thethermostatic switch I08 the contacts H6 and I I9 are opened thusbreaking the ignition circuit through the relay coil 33 which is howevermaintained by the holding circuit heretofore described and the openingof the contacts I I5 and H8 will break the circuit through the heatercoil I5 and the ignition transformer I4. When the contacts I and II"I ofthe thermostatic switch I08 are closed a second circuit is establishedfor the energization of the fuel valve IT. This second fuel valvecircuit runs from the transformer secondary 22 by way of conductors 23and I40 to the valve I.'I

=and'by conductor I42, the closed contacts II! and I 20 of thethermostatic switchI'OB, the conductors I06 and 44, the closed contactsand 10 31 of the relay switch 34, and the conductor 51, the circuitterminating back at the transformer secondary 22.

In summation, it is seen that when the thermostat 25 closes calling forheat the relay switch 34 is energized and closed thereby energizing theheater coil !5. When the temperature of the fuel vaporization member I0reaches a sufficient predetermined value the thermostatic switch I29closes energizing the circuits through the blower motor and the ignitiontransformer primary I3 thereby preparing the system for the ignition offuel. Upon the occurrence of sparks at the spark ignition IS in theburner not 2 the gas tube warp switch is activated thus completing thecircuit for the energization of the fuel control valve I1 whereupon fuelis admitted to the fuel well portion 3. When the fuel admitted to thefuel well portion 3 is vaporized and ignited in the pot 2 thetemperature of the jacketed air space surrounding the pot will risecausing the thermostatic switch I08 to open the contacts controlling thecircuits to the heater coil I5 and the ignition transformer primary I3thereby de-energizing the same and closing a circuit for continuedenergization of the fuel control valve. During combustion, as in theother form of the invention, heat for the vaporization of fuel enteringthe fuel Well portion 3 at the hollow end portion of the vaporizationmember I0 is supplied by conduction from the rod portion I 2 in the zoneof combustion.

What is claimed and is desired to be obtained by Letters Patent of theUnited States is:

1. In a control system for a liquid fuel burner an electricallycontrollable valve for controlling the supply of fuel to said burner,heating means for vaporizing fuel in said burner prior to ignitionthereof and including electrical heating means therefor, an electricspark ignition for said burner, means responsive to the generation of apredetermined temperature by said electrical heating means and operableto cause the energization of said ignition, means responsive to theoccurrence of ignition sparks in said burner and operable to open saidfuel supply control valve, means responsive to the occurrence of apredetermined temperature in said burner and operable to de-energizesaid ignition and said electrical heating means and to maintain saidfuel supply control valve, relay switch means controlling energizationof said system, a room thermostat controlling operation of said relayswitch means, and said last-named responsive means including switchmeans opened by response to said predetermined temperature to preventthe initial energization of said relay switch means while said burner ishot.

2. In a control system for a liquid fuel burner, an electricallycontrollable valve for controlling the supply of fuel to said burner, amassive metallic member operable upon, heating to vaporize fuel in saidburner, an electrical resistance heater for said metallic member,electrically operable air supply means for said burner, an electricspark ignition for said burner, a circuit for said ignition, athermostatic switch in said ignition circuit operable in response to thegeneration of a predetermined temperature by said heater to energizesaid ignition circuit, means including automatic switch means responsiveto the occurrence of sparks in said burner and operable to energize saidelectrically controllable valve for opening movement thereof, a secondthermostatic switch responsive to the occurrence of a predeterminedtemperature in said burner and operable to denergize said ignition andsaid heater and to continue energization of said fuel supply controlvalve to hold the same open, means including a room thermostat forcontrolling ener gization of said system, and said last namedthermostatic switch including switch contacts in series with saidthermostat and operable to prevent initial energization of said systemby said thermostat when the temperature in said burner is above apredetermined value.

3. A pot-type liquid fuel burner having a jacketed air space forsupplying air to said burner and having a control system thereforcomprising a controllable electric blower for supplying air to saidjacketed air space, an electrically controllable valve for controllingthe supply of fuel to the pot of said burner, a massive metallic memberpositioned in the pot of said burner and operable upon heating tovaporize fuel conducted thereagainst, an electrical resistance heaterfor said metallic member, an electric spark ignition for said burner,circuits for said ignition and said blower, a thermostatic switchclosable in response to the generation of a predetermined temperature bysaid heater to energize said ignition and said blower circuits, meansincluding automatic switch means responsive to the occurrence ofignition sparks in said burner and operable to energize saidelectrically control-- lable valve for opening movement thereof, asecond thermostatic switch positioned in said jacketed air space andresponsive to the occur rence of a predetermined temperature in saidburner and operable to deenergize said ignition and said heater and tocontinue energization of said fuel supply control valve to hold the sameopen, means including a room thermostat for controlling energization ofsaid system, and said last named thermostatic switch including switchcontacts in series with said thermostat and operable to prevent initialenergization of said system by said thermostat when the temperature insaid burner is above a predetermined value.

4. A control system for a liquid fuel burner having a jacketed air spacefor supplying air to said burner comprising a burner pot having a fuelwell portion, a controllable electric blower for supplying air to saidjacketed air space, an electrically controllable valve for controllingthe supply of fuel to said fuel well portion, a massive metallic memberpositioned in said fuel well portion and extending upward through saidpot and operable upon heating to vaporize fuel supplied to said fuelwell portion, an electrical resistance heater for said metallic member,an electric spark ignition for said burner, circuits for said ignitionand said blower, a thermostatic switch positioned adjacent said fuelwell portion and closable in response to the generation of apredetermined temperature by said heater to energize said ignition andsaid blower circuits, means including an automatic switch responsive to.the occurrence of electrical ignition sparks in said burner and operableto energize said electrically controllable valve for opening movementthereof, a second thermostatic switch positioned in said jacketed airspace and responsive to the occur rence of a predetermined temperaturein said burner and operable to de-energize said ignition and said heaterand to continue energization of said fuel supply control valve to holdthe same open, relay switch means controlling energizetion of saidsystem, a room thermostat controlling energization of said relay switchmeans,

and said last-named thermostatic switch including switch contacts inseries with said room thermostat and operable to prevent initialenergization of said relay switch means while the temperature of saidburner is above said predetermined temperature.

5. A control system for a liquid fuel burner comprising a burner pothaving a fuel well portion, a constantly running electric blower forsupplying air to said pot, an electrically controllable valve forcontrolling the supply of fuel to said fuel well portion, a massivemetallic member positioned in said fuel well portion and extendingupward through said pot, an electrical resistance heater for saidmetallic member, said metallic member being heated initially by saidheater and subsequently by flame in said pot and being operable uponsaid heating to vaporize fuel in said fuel well portion, an electricspark ignition for said burner, an electric circuit for said ignition, athermostatic switch positioned adjacent said fuel well portion andclosable in response to the generation of a predetermined temperature bysaid heater to energize said ignition, circuit means including automaticswitch means responsive to the occurrence of electrical ignition sparksin said burner and operable to energize said electrically controllablevalve for opening movement thereof, a second thermostatic switchpositioned adjacent said fuel well portion and responsive to thetemperature of said metallic member when heated by the occurrence offlame in said pot and operable to deenergize said ignition and saidheater and to continue energization of said fuel supply control valve tohold the same open, relay switch means controlling energization of saidsystem, a room thermostat controlling energization of said relay switchmeans, and said last named thermostatic switch including switch contactsin series with said room thermostat and controlling energization of saidrelay switch means.

6. In a liquid fuel burner and control system therefor, a vaporizingpot, electrically controlled means for supplying fuel to said pot, ametallic member positioned in said pot and extending upward into thezone of combustion and operable upon heating to vaporize fuel enteringsaid pot, electrical means operable upon energization to heat saidmetallic member for initial operation, said metallic member beingsubsequently heated by flame after the occurrence of the same in saidpot, means responsive to the heat of flame in said pot and operable tode-energize said electrical heating means, means including a roomthermostat for controlling energization of said system, and saidlast-named responsive means including switch means connected in serieswith said thermostat and operable to prevent initial energization ofsaid system by said thermostat so that said fuel supply means may not beenergized while the temperature of said burner pot is in excess of apredetermined value.

'7. A liquid fuel burner having a. vaporizing pot, a fuel well openingupwardly into said pot, a metallic member having an enlarged hollow endportion and a solid rod end portion for conducting heat to said hollowend portion, said enlarged hollow end portion being positioned in saidfuel well and forming with the walls of said fuel well an annular spaceof small cross section, said solid rod end portion extending upwardlythrough said pot into the zone of combustion, said metallic member beingoperable upon heating to vaporize fuel in said annular space, an

electrical resistance heater in said hollow end portion and operableupon energization to heat the same for initial operation, said hollowend portion being heated by conduction of heat from said solid rodportion after the occurrence of combustion in said pot, means responsiveto the heat of combustion in said pot and operable to de-energize saidelectrical resistance heater, an electrically operated valve controllingthe supply of fuel to said burner, electric circuit means forcontrolling said valve, means including a room thermostat controllingenergization of said electric circuit means, and said responsive meansincluding switch means connected in series with said room thermostat andoperable to prevent initial energization of said electric circuit meansby said room thermostat when the temperature of said burner pot is inexcess of a predetermined value.

8. In a control system for a liquid fuel burner, electrically operatedmeans for controlling the supply of fuel to said burner, a fuelvaporizing member having an electric heating coil and operable tovaporize fuel prior to ignition thereof, an electric spark ignition insaid burner and having an energizing transformer; electric circuits forsaid fuel supply means, said electric heating coil, and saidtransformer; a thermostatic switch in said transformer circuit andoperable to energize said ignition in response to heat of said heatingcoil, means in said fuel supply circuit responsive to the occurrence ofsparks in said burner and operable to actuate said fuel supply means, asingle pole double throw switch having a pair of initially closedcontacts in a portion common to said ignition transformer circuit andsaid heating coil circuit, a second circuit for said fuel supply meansindependent of said spark responsive means, said last-named switchhaving a pair of initially open contacts in said second fuel supplycircuit; thermostatic means responsive to the heat of combustion in saidburner and operable to move said last-named switch to deenergize saidignition and said heating coil circuits, and to energize said secondfuel supply means circuit; a relay switch having a pair of initiallyopen contacts in series with the movable pole of said last-named switch,an energizing circuit for the coil of said relay switch, a roomthermostat in said relay coil circuit, an initially closed switch insaid relay coil energizing circuit and operated by said combustionresponsive thermostatic means, and circuit means including a switchclosed upon energization of said relay coil to shunt said last namedswitch.

9. In a control system for a liquid fuel burner, means for controllingthe supply of fuel to said burner, means for vaporizing fuel in saidburner prior to ignition thereof and including electrical energizationmeans therefor, electrical means for igniting fuel in said burner, meansresponsive to the heating of said fuel vaporization means and operableto control the energization of said fuel supply controlling means, meansresponsive to the heat output of said burner and operable to de-energizesaid ignition means and said fuel vaporization means, a relay switchhaving a coil and circuit therefor and having contacts controllingenergization of said system, a room thermostat controlling energizationof said relay coil, switch means in said relay coil circuit and openedby said last-named responsive means to prevent initial energization ofsaid system by operation of said thermostat while said burner is above apredetermined temperature, and said relay switch having contactsconnected in parallel with said last named switch means to provide aholding circuit for said relay coil during normal operation of saidburner.

FRED B. AU'BERT.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,382,721 Gerstenberger June 28, 1921 1,594,020 Smith July 27,1926 1,901,271 Taft Mar. 14, 1933 1,968,360 Sturgis July 31, 19341,985,991 Harrington Jan. 1, 1935 2,108,770 Kriechbaum Feb. 15, 19382,159,257 Danuser et a1. May 23, 1939 2,301,446 Ott Nov. '10, 19422,406,185 Aubert Aug. 20, 1946 2,432,143 DeLancey Dec. 9, 1947 2,438,275Fell et a1. Mar. 23, 1948 2,460,451 Farrell Feb. 1, 1949

